What should we tell people about the AMNH apatosaurine?

May 9, 2015

AMNH 460 left anterolateral view

Apatosaurines on the brain right now.

I’ve been thinking about the question raised by Jerry Alpern, a volunteer tour guide at the AMNH, regarding the recent Tschopp et al. (2015) diplodocid phylogeny. Namely, if AMNH 460 is now an indeterminate apatosaurine, pending further study, what should the museum and its docents tell the public about it?

Geez, Apatosaurus, it’s not like we’re married!

I think it’s a genuinely hard problem because scientific and lay perspectives on facts and hypotheses often differ. If I say, “This animal is Apatosaurus“, that’s a fact if I’m talking about YPM 1860, the genoholotype of Apatosaurus ajax; it would continue to be a fact even if Apatosaurus was sunk into another genus (as Brontosaurus was for so long). We might call that specimen something else, but there would always be a footnote pointing out that it was still the holotype of A. ajax, even if the A. part was at least temporarily defunct – the scientific equivalent of a maiden name.* For every other specimen in the world, the statement, “This animal is Apatosaurus” is a hypothesis about relatedness, subject to further revision.

* This is going to sound kinda horrible, but when one partner in a marriage takes the other’s surname, that’s a nomenclatural hypothesis about the future of the relationship.

Apatosaurine cervicals are the best cervicals.

Apatosaurine cervicals are the best cervicals.

Fuzzy science

Things that look fairly solid and unchanging from a distance – specifically, from the perspective of the public – often (always?) turn out to be fairly fuzzy or even arbitrary upon closer inspection. Like what is Apatosaurus (beyond the holotype, I mean) – or indeed, what is a planet.** There is no absolute truth to quest for here, only categories and hypotheses that scientists have made up so that we can have constructive conversations about the crazy spectrum of possibilities that nature presents us. We try to ground those categories and hypotheses in evidence, but there will always be edge cases, and words will always break down if you push them too hard. Those of us who work on the ragged frontier of science tend to be fairly comfortable with these inescapable uncertainties, but I can understand why people might get frustrated when they just want to know what the damned dinosaur is called.

** Triton, the largest body orbiting Neptune, is almost certainly a captured Kuiper Belt object, and it’s bigger than Pluto. Moon or planet? Probably best to say a former dwarf planet currently operating as a satellite of Neptune – but that’s a mouthful (and a mindful, if you stop to think about it), not a short, convenient, easily-digestible label. Any short label is going to omit important information. This is related to the problem of paper title length – below some threshold, making something shorter means making it incomplete.

What I would say

I suppose the short version that is most faithful to the Tschopp et al. results is:

This skeleton (AMNH 460) might be Apatosaurus or Brontosaurus or a third, new thing – scientists aren’t sure yet.

A reasonable follow-up sentence – and an answer to the inevitable “Why not?” – would be:

They have to look at 477 anatomical details for lots of skeletons and weigh all the evidence, and that takes time.

Personally, if I was talking to museum visitors I would lean in conspiratorially and say:

If you want to call it Apatosaurus or Brontosaurus, go ahead – those are both ‘live’ hypotheses, and even the world’s experts on this problem can’t tell you that you’re guessing the wrong way – at least not yet.

And if there was a kid in the group, I’d add:

Maybe you’ll be the one to figure it out!

What would you say?

My neck is fat.

My neck is fat.

P.S. I wouldn’t change the signage. It could still turn out to be Apatosaurus, and the Tschopp et al. results do not lend themselves to easy label-ification.

P.P.S. With some modification for taxonomy, all of this applies to the Field Museum diplodocid FMNH P25112 as well.


Tschopp E, Mateus O, Benson RBJ. (2015) A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda) PeerJ3:e857 https://dx.doi.org/10.7717/peerj.857

19 Responses to “What should we tell people about the AMNH apatosaurine?”

  1. James A. Stearns Says:

    I think all the points mentioned were good and valid. However, if anyone were to insist that a name be used, I’d use Brontosaurus. All of the specimens assigned to Brontosaurus come from the lower levels of the Morrison and all those assigned to Apatosaurus come from the upper levels. This specimen came from the lower levels of the formation and is thus much more likely to be Brontosaurus.

    (Also, it was traditionally called Brontosaurus and has been the “iconic” Brontosaurus ever since it was first mounted; not that this has any real value)

  2. Allen Hazen Says:

    If I were a docent at the AMNH and a visitor asked me to explain things, I think I’d say something like this:

    “Apatosaurus and Brontosaurus are about as closely related as deer and elk, and we don’t know which this particular individual is. It might even be a moose.”

    (Choice of modern taxa for the analogy is more or less arbitrary. If you thought– as of course none of us do– that there was an agreed-upon objective measure of how closely related species in a subfamily are, this might even understate the relatedness: Americans when the hear “deer” tend to think of the White-tailed Deer (Odocoileus virginianus) and when they hear “elk” to think of the Wapiti (Cervus canadensis), which are assigned to different subfamilies of the Cervidae. But only with a very interested visitor, on a quiet day, would I go into that sort of detail!)

  3. Ben Says:

    Thanks for weighing in on this – I’ve been getting this question from a lot of visitors over the lats few weeks and it’s very helpful to have a less arm-wavy answer to point to. I also think it’s important to come clean when a mount is a composite – the AMNH sauropod is assembled from at least four specimens found in two states, so there’s always the possibility that visitors are looking at more than one taxon.

  4. Chase Says:

    As Ben said above, the skeleton on display is a composite. AMNH 460 is most likely Brontosaurus sp. as it displays the “fat neck” which is characteristic of the genus. If I were to explain it to those who came to my museum, I would say something like the following: “This mount, for the moment, is thought of as a close relative of Apatosaurus, but we can’t be sure if it is Apatosaurus or Brontosaurus. However, this mount is composite and displays bones taken from multiple specimens. This just goes to show how much we are still learning about these animals. ” This way, you could communicate the ever-changing state of paleontology as well as communicate the history of the specimen.

  5. Fuzzy astronomy doesn’t enter into the discussion. Triton is a moon. It qualifies because it matches the generalized criteria (the IAU doesn’t qualify a moon because frankly it hasn’t had to) of being a moon, just as Phobos and Deimos and all the shepherd moons of the gas giants do, by being a large body that orbits a planet (which orbits a star). Moons also clear their local environment of debris, so tend not to be part of ring debris, but often create the margins to rings by their gravity and motion.


    You can just choose not to accept Tschopp et al. and say there’s no effective difference between their preferred useage for Apatosaurus and Brontosaurus. This can be done by introducing new characters into the analysis that reveal more or reduce other systematic “distance” between the taxa in question.

    Now, imagine if we used this “method” for Triceratops and Torosaurus. Evidence mounts that many specimens, often explicitly found by systematic analysis to be “unique” and potentially worthy of nomenclature are, in fact, possibly ontogenetic variants. The argument is still ongoing (which is good) but it suggests the issue is more complex than just “Ooo, new analysis that say X is now Y, and G is … something!” And because of this ambiguity, we should be far more careful in accepting the taxonomy.

  6. LeeB Says:

    Why not approach the question head on with a sign saying Apatosaurus, Brontosaurus or something else?

    Then explain that most names were given originally to incomplete material and later more complete mounted specimens were thought to be one of the same few species.
    However more research has shown that there are more genera and species and as a result less than half the museums with mounted diplodocids can be sure of the correct name of their specimen.
    Your specimen might even belong in a new genus; we can’t be sure yet.

    Scientists are working on this but because of the size and difficulty of access to the specimens and because the good specimens are in museums scattered across North America, Europe and Asia it will take time and money to sort out.

    Say that when you know for sure it’s correct name the museum will hold a public naming ceremony for your specimen.

  7. Matt Wedel Says:

    Fuzzy astronomy doesn’t enter into the discussion. Triton is a moon. It qualifies because it matches the generalized criteria (the IAU doesn’t qualify a moon because frankly it hasn’t had to) of being a moon

    For crying out loud, Jaime, could you have missed my point any more comprehensively? I say that simple labels will often fail to convey the subtlety of nature because the world is complicated, and you reply that no, it isn’t, because labels are simple.

    In point of fact, this is at least some actual discussion about this among professional astronomers, with some people advocating alternative schemes to the one that we have now. For example the proposal by planetary geologist Alan Stern that we refer to all hydrostatically rounded objects that aren’t stars as planets, with the ones orbiting other planets (like most moons, including Luna and Triton) being referred to as ‘satellite planets’. Stern is the PI on the New Horizons mission to Pluto so he’s not some kind of outsider crank, and although his proposal has not been adopted yet, it would be premature to assume that it or something like it will never be adopted.

    Yes, Triton is a moon right now. I said so right in the post: “currently operating as a satellite of Neptune”. But it also used to be a planet, almost certainly. For the purposes of the present discussion, I don’t care what the IAU calls it – that would be like saying two months ago that the content of Apatosaurus isn’t fuzzy because Brontosaurus doesn’t exist. The IAU can and does change the labels on things, just as the ICZN does, and it’s not beyond the bounds of possibility that some future nomenclatural scheme for solar system bodies (like Stern’s) will recognize Titan as something else. The point is that simple labels are prone to breaking down when faced with the real complexity of nature. That a simple label (‘moon’, Apatosaurus) is temporarily applied to something with a complex history (Triton, apatosaurine diversity) does not contradict that point – in fact, it exemplifies it.

  8. Andrew ALPERN Says:

    You explain well about the bright-line distinctions that the public seeks, but the fuzziness and imprecision of the continually changing world of sauropod knowledge. Much of the time when you ask a question of a lawyer (I am one) the answer he will give you is “It depends.” Laymen usually think that something is legal or illegal, right or wrong. But everything is always black or white except when it’s not, which is almost all the time. I have perpetually had a hard time explaining that adequately to non-lawyers. How gratifying to know that the problem isn’t encountered only in the legal profession. Incidentally, I am Jerry Alpern’s brother.

  9. Matt Wedel Says:

    Nice to hear from you, Andrew. I’ve recently had the opportunity to talk to some lawyers, for reasons I can’t get into right now, and you’re absolutely correct. What I thought was legally pretty open-and-shut turned out to be, well, complicated.

    I know some people get irritated when other people say, “It’s complicated”, but I think it has to do with what people mean by that. Often “it’s complicated” is used to end a conversation about a topic, like, “I thought your ex was out of the picture?” “It’s complicated.” Or, if not end the conversation, at least flag that particular digression as likely too hairy to get into right now.

    But for scientists – and lawyers, and probably anyone in a sufficiently specialized field – “it’s complicated” is often where the real conversation starts.

  10. Andrew ALPERN Says:

    When your four-year-old son asks about sex you give him a very-much-simplified answer. When your teenager asks about it he gets a much more detailed reply appropriate to his situation and to the unasked specific questions you know are on his mind. When your answer is “It’s complicated,” that a signal that the subject is a very grown-up one that has many twists and turns, and will take far longer to explain adequately than you have available for it at that moment. It also says that you have a very significant amount of knowledge on the subject that you will share only if the questioner is prepared for the considerable effort it will take to absorb and understand that knowledge.

  11. […] a recent post I showed some photos of the mounted apatosaurine at the American Museum of Natural History in New […]

  12. Matt Wedel Says:

    Yes, good point. I didn’t mean to imply that “it’s complicated” was only for people in technical fields. It’s sort of a conversational warning label: there’s a lot to keep track of here, and you may need to immerse yourself in it before you know if that immersion was worth it or not.

  13. Graeme Worth Says:

    I’d like to raise a question that is related to the Apatosaurus/Brontosaurus issue and to lumpers/splitters more generally. In many cases new species and even genera are named based on fairly slight differences between skeletal parts, often with few specimens of any of the comparative “genera”, and hence no real idea of potential natural variation within or between any of the campared specimens.
    We now have several examples of large, monospecific bonebeds (Triceratops, Pachyrhinosaurus, ??) as well as hundreds of specimens of some taxa (Confusciusornis), and in terms of extant animals where there is little argument that we are dealing with one species (African elephant, various birds, ??). To anyone’s knowledge, have any of these ever been analysed specifically to address the question of how much variation we might reasonably expect to find in the morphology of various skeletal elements, with a view to then apply these ‘variability estimates’ to the question of taxonomy?

  14. Matt Wedel Says:

    Graeme, that is a very good question. The only study of that sort that I am familiar with is Shubin et al. (1995), “Morphological variation in the limbs of Taricha granulosa“, which you can download for free here. In 1991 a small pond in Marin County, California, froze completely and killed over 500 rough-skinned newts. Shubin et al. collected, cleared, and stained 452 of the newts and documented the morphology of 903 forelimbs and 902 hindlimbs. They found all kinds of crazy ossification patterns in the hands and feet, including atavistic patterns typical of different groups of Paleozoic amphibians and other basal tetrapods.

    The largest human skeleton collections probably approach that level of variation, but they don’t usually represent genetically interacting populations. The cool thing about the Shubin et al. newts is that they were all from one pond at one time, and the sample included 90% of the population of that pond.

    Anyone else know of similar studies in other animals? I’d be especially curious to know about skeletal variation in mammals and birds.

    I can tell you from working in the human anatomy lab that you will often see at least one variant muscle in a group of only 8-10 people, and that in a group of 100-150 cadavers you will probably find at least one variation in the muscles, vessels, or nerves that has not previously been documented in the literature. But most of these don’t leave any skeletal traces, and I don’t know what level of skeletal variation you’d see in the same sample size.

  15. […] we accept that the distinctive ventral projections of the gigantic and ventrally displaced cervical ribs of apatosaurs were likely the base of some form of soft-tissue rugosity — such as keratinous horns like […]

  16. […] of the giant Oklahoma Apatosaurus – which I guess should now be called the giant Oklahoma apatosaurine until someone sorts out its phylogenetic position – and the darn-near-T. rex-sized […]

  17. Tom Johnson Says:

    I was reviewing Tschopp et. al. (which, let me hastily confess, is a bit over my head) and it occurred to me that, not only are we not sure about the generic identities of the AMNH and FMNH sauropod exhibits, it seems that (going by Tschopp et. al.) we are sure of very few Apatosaurus and Brontosaurus specimens other than the type specimens. AMNH has mounted the yet-unnamed sauropod publicized as “The Titanosaur.” Why not just call AMNH 460 the Apatosaurine for the time being?

    No, I don’t like the sound of it either. And despite the sophistication of the analyses in Tschopp et. al., 2015, it seems like, out of a relatively small sample (about 10) of relatively complete Apatosaur/Brontosaurs, there are few “matches.” Maybe this is oversplitting, and maybe there were a lot of different sauropod genera living near the same time and place.

    Both AMNH 460 and FMNH P25112 appear to be somewhat inaccessible for research, being mounted and restored in plaster and all. So it may be a while. Bummer!

    Thanks for the interesting posts and comments!

    Tom Johnson

  18. Mike Taylor Says:

    Tom, you’re right, we are certain of very little. That is the nature of palaeontology. If in the past it appeared that we were more certain, that was just because we we’re seeing the problems as clearly as we do now. Time was, if H. F. Osborn said is was an Brontosaurus, it was a Brontosaurus, end of. Now that we have rigorous methods that help us determine such things, the uncertainty that was always there is being surfaced.

    Just calling AMNH 460 “the apatosaur” would be fine by me.

    Yes, a big problem with sauropod research in general is inaccessibility of specimens. For some reason, that is especially true of apatosaurs — perhaps because so many important specimens were mounted long ago, when artistic concerns trumped scientific ones when restoring bones!

  19. […] Long considered a specimen of Brontosaurus excelsus or Apatosaurus excelsus, AMNH 460 was referred to Apatosaurus ajax by Upchurch et. al. in 2005. In the most comprehensive analysis of diplodocid phylogeny to date, Tschopp et. al. (2015) found AMNH 460 to be an “indeterminate apatosaurine” pending a “detailed analysis of the specimen.” What to call it? Oh, yeah, that’s been covered in another post! […]

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